Method and system for fast digital channel change utilizing time-stamp management

ABSTRACT

A video stream demultiplxer receives video streams comprising a selected current content channel and one or more adjacent content channels. Time stamp management is concurrently performed on the adjacent content channels while decoding the selected current content channel. Timing information such as Decoding Time Stamp (DTS) and Presentation Time Stamp (PTS) values, and/or random access points (RAPs) may be determined for pictures stored for the selected current content channel and the adjacent content channels. The determined timing information is utilized to determine a Program Clock Reference (PCR) value for each of the selected current channel and the adjacent channels for channel monitoring. A timebase, derived from a PCR rate that is determined based on the determined PCR value, is determined for decoding the selected current content channel. An adjacent content channel, which is primed during decoding of the selected current content channel, may be directly decoded for display if selected.

CROSS-REFERENCE TO RELATED APPLICATIONS/INCORPORATION BY REFERENCE

This application makes reference to, claims priority to and claimsbenefit from and is a continuation of U.S. patent application Ser. No.12/874,424, entitled “Method and System for Fast Digital Channel ChangeUtilizing Time-Stamp Management,” filed Sep. 2, 2010; which claimspriority to U.S. Provisional Patent Application Ser. No. 61/360,843filed on Jul. 21, 2010, each of which is incorporated herein byreference in its entirety.

This application makes reference to:

U.S. application Ser. No. 12/189,022 filed on Aug. 8, 2008,

U.S. application Ser. No. 12/105,127 filed on Apr. 17, 2008, and

U.S. application Ser. No. 10/926,374 filed on Aug. 25, 2004.

Each of the above stated applications is hereby incorporated herein byreference in its entirety.

FIELD OF THE INVENTION

Certain embodiments of the invention relate to communication systems.More specifically, certain embodiments of the invention relate to amethod and system for fast digital channel change utilizing time stampmanagement.

BACKGROUND OF THE INVENTION

Channel change time is an important part of the user experience fordigital video or other digital image or content applications. Channelchange time represents a delay from the time that a viewer selects achannel for a digital video application to the time that correspondingvideo information is displayed to the viewer. Channel change time may bea function of many different elements such as tuner acquisition time,encryption descrambling, post-decode processing, and the time requiredto present the first picture to the viewer after finding a random accesspoint in a video stream. The random access point represents a point inthe video stream where a decoder may begin decoding successfully.

Normally, a channel change may comprise locating the random access pointand filling a compressed data buffer (CDB) with data starting from thisaccess point, decoding a coded picture, placing the decoded picture in adecoded picture buffer, and presenting the picture to the viewer. Thepicture is decoded and presented at a time indicated by clock referencessuch as a decoding time stamp (DTS) and a presentation time stamp (PTS)transmitted together with the coded picture.

Further limitations and disadvantages of conventional and traditionalapproaches will become apparent to one of skill in the art, throughcomparison of such systems with some aspects of the present invention asset forth in the remainder of the present application with reference tothe drawings.

BRIEF SUMMARY OF THE INVENTION

A method and/or system for fast digital channel change utilizing timestamp management, substantially as shown in and/or described inconnection with at least one of the figures, as set forth morecompletely in the claims.

These and other advantages, aspects and novel features of the presentinvention, as well as details of an illustrated embodiment thereof, willbe more fully understood from the following description and drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a block diagram of an exemplary video decoding system that maybe operable to support a fast digital channel change utilizing timestamp management, in accordance with an embodiment of the invention.

FIG. 2 is a diagram illustrating an exemplary video streamde-multiplexer that is operable to prime adjacent channels utilizingtime stamp management for a fast digital channel change, in accordancewith an embodiment of the invention.

FIG. 3 is an exemplary process for priming adjacent channels utilizingtime stamp management for fast digital channel change, in accordancewith an embodiment of the invention.

FIG. 4 is a block diagram illustrating exemplary steps that may beperformed by a video stream de-multiplexer to prime adjacent channelsutilizing time stamp management while decoding a current channel, inaccordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Certain embodiments of the invention may be found in a method and systemfor fast digital channel change utilizing time stamp management. Invarious embodiments of the invention, a video stream demultiplxer may beoperable to receive one or more video streams via a video decodingsystem. The received video streams may comprise a selected currentcontent channel and one or more content channels adjacent to theselected current content channel. Video primers may be utilized by thevideo stream demultiplxer to concurrently perform time stamp managementon each of the one or more adjacent content channels while decoding theselected current content channel. Pictures for the selected currentcontent channel and each of the adjacent content channels may be stored,respectively, in a coded data buffer that is communicatively coupled tothe video stream demultiplexer. Timing information such as Decoding TimeStamp (DTS) values, and Presentation Time Stamp (PTS) values, and/or oneor more random access points (RAPs) may be determined for the storedpictures of the selected current content channel and the adjacentcontent channels, respectively. A Program Clock Reference (PCR) valuemay be determined for each of the selected current content channel andthe adjacent content channels based on corresponding determined PTSvalues for channel monitoring. A PCR rate may be determined for theselected current content channel based on the determined PCR value toderive a timebase. The derived timebase provides a clock reference fordecoding pictures of the selected current content channel. The videoprimers may be operable to prime pictures for the adjacent contentchannels, during decoding of the selected current content channel, fordecoding and displaying. Pictures for one of the adjacent contentchannels may be directly decoded for display if the one of the adjacentcontent channels is selected.

FIG. 1 is a block diagram of an exemplary video decoding system that maybe operable to support a fast digital channel change utilizing timestamp management, in accordance with an embodiment of the invention.Referring to FIG. 1, there is shown a video decoding system 100. Thevideo decoding system 100 may comprise a demultiplexer (de-mux) 110, avideo decoder 120 and a display device 130.

The de-mux 110 may comprise suitable logic, circuitry, interfaces and/orcode that are operable to receive one or more video transport streams(TSs) and extract individual content channels, also called channels orprograms, from the received TSs. The received TSs may be in variousvideo compression formats such as, for example, MPEG-1, MPEG-2, MPEG-2,and/or H.264/AVC video compression formats. Time stamps such as, forexample, reference time stamps, Decoding Time Stamp (DTS) and/orPresentation Time Stamp (PTS) may be embedded in the received TS forcontrol or management of decode, display, and rate conversion fordesired channels or programs. The reference time stamps such as ProgramClock Reference (PCR) may set a time reference (timing) to assist thevideo decoder 120 and the display device 130 in presenting desiredchannels or programs on time, at the right rate, and withsynchronization. The DTS and the PTS may indicate the exact time instantwhere a video frame or picture needs to be decoded and/or presented tothe user, respectively. The DTS and the PTS are relative values and mayrely on reference time stamps such as the PCR for operation. Forexample, a current channel may be selected from one or more channels inthe received TSs based on device capabilities and/or user preferences.Pictures for the current channel may be decoded and/or presented ininstances where the difference of time stamps, for example, PTS-PCR, isachieved to a preset threshold value.

In an exemplary embodiment of the invention, the de-mux 110 may beoperable to concurrently store or buffer pictures of the current channelas well as each of the adjacent channels in the received TSs into acompressed data buffer (CDB) 110 a. The CDB 110 a may comprise suitablelogic, circuitry, interfaces and/or code that are operable to store andmanage pictures or frames in the received TSs. The CDB 110 a iscommunicatively coupled to the de-mux 110. The CDB 110 a may compriseRAM, ROM, low latency nonvolatile memory such as flash memory and/orother suitable electronic data storage capable of storing data andinstructions. The de-mux 110 may search for or identify timinginformation such as PTSs and/or random access points (RAPs) from thestored pictures in the CDB 110 a for the current channel and theadjacent channels. A RAP of a specific channel or program may indicateinformation regarding a location within the specific channel or programfor random access of the specific channel or program. The de-mux 110 maybe operable to calculate PCR values based on the correspondingidentified PTSs for the current channel and each of the adjacentchannels, respectively.

In an exemplary embodiment of the invention, the de-mux 110 may beoperable to recover a clock for decoding the current channel at adesired rate. In this regard, the de-mux 110 may be operable todetermine a PCR rate specifically for the current channel based on acorresponding PCR value. A PCR rate is a sample rate indicating thenumber of times per second the PCR may appear in the received TSs. Thedetermined PCR rate may be provided as a timebase or a reference clockto the decoder 120 for decoding the current channel at the right rate.

In an exemplary embodiment of the invention, the de-mux 110 may beoperable to monitor or track pictures of the adjacent channels utilizingcorresponding PCR values. In this regard, the de-mux 110 may be operableto perform time stamp management on pictures of each of the adjacentchannels to prime or prepare the adjacent channels for a fast channelchange while the current channel is being decoded. Time stamp managementcomprises functions or features providing accurate control of decode,display, and rate conversion for desired channels. In this regard,pictures of the adjacent channels within the CDB 110 a may be managedbased on associated time stamp information such as the differencebetween PTSs and PCRs. For example, pictures of each of the adjacentchannels may be discarded if PTS≤PCR. The de-mux 110 a may maintainpictures of the specific adjacent channels in the CDB 110 a if PTS>PCR.In instances where a specific adjacent channel is selected by the user,the de-mux 110 may be operable to immediately start decoding one or morepictures of the specific adjacent channel if they are ready fordecoding.

The video decoder 120 may comprise suitable logic, circuitry, interfacesand/or code that are operable to decompress pictures of individualchannels in the received TSs to recover desired channels or programsthat may be present at the display device 130.

The display device 130 may comprise suitable logic, circuitry,interfaces and/or code that are operable to present pictures of desiredprograms or channels to users.

In an exemplary operation, the de-mux 110 may be operable to receive TSscomprising pictures of a current channel as well as pictures of one ormore adjacent channels. The de-mux 110 may concurrently store picturesof the current channel and each of the adjacent channels into the CDB110 a. The CDB 110 a may be configured to manage pictures of eachindividual channel in the received TSs. Timing information such as PTSsand/or RAPs may be determined or identified for the current channel andthe adjacent channels such that pictures of desired channels may bedecoded and presented on time and with synchronization. PCR values maybe calculated or determined for the current channel and each of theadjacent channels, respectively, by monitoring the incoming PCR on eachadjacent channel. The de-mux 110 may be operable to prime the adjacentchannels by performing time stamp management on each of the adjacentchannels while decoding the current channel. For example, de-mux 110 maybe operable to concurrently decode the current channel and monitor eachof the adjacent channels utilizing corresponding PCR values. Pictures ofthe adjacent channels may be primed such that an adjacent channel, ifselected, may have a picture which may be immediately decoded anddisplayed because the RAP may be present and the buffer level may bealready set to the desired level via the video decoder 120 and thedisplay device 130.

FIG. 2 is a diagram illustrating an exemplary video streamde-multiplexer that is operable to prime adjacent channels utilizingtime stamp management for a fast digital channel change, in accordancewith an embodiment of the invention. Referring to FIG. 2, there is showna de-mux 200 comprising a processor 210, a coded data buffer (CDB) 220,and a memory 230.

The processor 210 may comprise suitable logic, circuitry, interfacesand/or code that are operable to detect and/or handle individual contentchannels or programs in TSs received via the video decoding system 100.In various exemplary embodiments of the invention, the processor 200 maybe operable to concurrently store or buffer pictures in the received TSsinto the CDB 220. The stored pictures comprise pictures of the currentchannel and one or more adjacent channels in the received TSs. Timinginformation such as PTSs and RAPs may be detected or determined for eachchannel. A PCR rate may be determined for the current channel based oncorresponding calculated PCR value. The determined PCR rate may beutilized as a timebase or a reference clock for decoding pictures of thecurrent channel at the right rate. The processor 210 may monitor ortrack pictures for the current channel as well as each of the adjacentchannels utilizing the PCR values. In this regard, the processor 210 maybe operable to perform time stamp management on each of the adjacentchannels during decoding of the current channel to prime the adjacentchannels for a fast channel change. The processor 210 may assign adifferent video primer to one of the adjacent channels. For example,video primers 212-216 may be utilized to handle or prime pictures fordifferent adjacent channels, respectively.

A video primer such as the video primer 212 may comprise suitable logic,circuitry, interfaces and/or code that are operable to perform timestamp management on pictures for an adjacent channel. The video primer212 may prime or prepare the adjacent channel, if selected, for animmediate decode and display. The video primer 212 may be operable toroute and/or store pictures of the adjacent channel to the CDB 220during decoding of the current channel. The video primer 212 may beoperable to perform time stamp management by monitoring PTS/PCRdifferences for stored pictures of the adjacent channels. The videoprimer 212 may prime the adjacent channels via the time stamp managementfor a fast channel change over a selected adjacent channel.

The CDB 220 may comprise suitable logic, circuitry, interfaces and/orcode that are operable to store and manage pictures or frames of one ormore channels in the received TSs. Pictures of different channels may bemanaged in the CDB 220 individually. For example, pictures of thecurrent channel and each of the adjacent channels may be stored in acurrent channel buffer 228 and adjacent channel buffers 222-226,respectively. The CDB 220 may comprise RAM, ROM, low latency nonvolatilememory such as flash memory and/or other suitable electronic datastorage capable of storing data and instructions.

The memory 230 may comprise suitable logic, circuitry, interfaces and/orcode that are operable to store and manage data and/or other informationutilized by the processor 210. For example, the memory 210 may beutilized to store executable instructions to prime adjacent channelsduring decoding of the current channel. The memory 210 may comprise RAM,ROM, low latency nonvolatile memory such as flash memory and/or othersuitable electronic data storage capable of storing data andinstructions.

In an exemplary operation, the processor 210 may be operable to handleindividual channels in TSs received via the video decoding system 100.The processor 200 may be operable to concurrently prime adjacentchannels via the video primers 212-216 while decoding a current channel.Each adjacent channel may be handled or managed by a different videoprimer. A video primer such as the video primer 212 may be operable toperform time stamp management on one adjacent channel during decoding ofthe current channel. The video primer 212 may be operable to route orstore pictures of each of the adjacent channels to the CDB 220,respectively. The video primer 212 may be operable to monitor PTS/PCRdifferences over the stored pictures of the adjacent channels such thatan adjacent channel, if selected, may be ready for immediate decode anddisplay.

FIG. 3 is an exemplary process for priming adjacent channels utilizingtime stamp management for fast digital channel change, in accordancewith an embodiment of the invention. Referring to FIG. 3, there is shownan adjacent channel priming processing. It may be assumed in thisexample that two TSs 310 and 320 may be received by the de-mux 200 andeach received TS comprises two channels. Pictures of a current channel,in the TS 310, for example, may be stored in a current channel buffer314. Pictures for each of the adjacent channels may be stored inadjacent channel buffers 312, 322 and 326, respectively.

PCR values may be determined for the current channel and each of theadjacent channels. Pictures in the current channel buffer 314 and eachof the adjacent channel buffers 312, 322 and 326 may be monitored ortracked utilizing corresponding PCR values. With regard to the currentchannel, a PCR rate may be calculated based on the determined PCR value.The determined PCR rate may be utilized as a timebase or as a referenceclock for the video decoder 318 to decode pictures stored in the currentchannel buffer 314 at right rate.

In various exemplary embodiments of the invention, each adjacent channelmay be managed by a particular video primer during decoding of thecurrent channel. For example, video primers 316, 324 and 328 may beutilized to prime pictures in the adjacent channel buffers 312, 322 and326, respectively, for direct decoding once one of the adjacent channelsis selected. Time stamp management may be performed via the videoprimers 316, 324 and 328 on pictures in the adjacent channel buffers312, 322 and 326, respectively. Each of the video primers 316, 324 and324 may be operable to monitor time stamp differences such as PTS-PCR ofpictures in each of the adjacent channel buffers 312, 324 and 326.Pictures may be discarded if PTS>PCR and the next RAP are present. Inthis way, each of the adjacent channel buffers 312, 324 and 326 mayalways have a RAP ready to decode. Pictures corresponding to PTS>PCR maybe maintained within associated adjacent channel buffers. In thisregard, pictures that are ready to be decoded, in the adjacent channelbuffer 312, for example, may be provided to the video decoder 318 forimmediate decoding and display if an associated adjacent channel isselected.

FIG. 4 is a block diagram illustrating exemplary steps that may beperformed by a video stream de-multiplexer to prime adjacent channelsutilizing time stamp management while decoding a current channel, inaccordance with an embodiment of the invention. Referring to FIG. 4, theexemplary steps start with step 402. In step 402, the de-mux 200 may beoperable to prime adjacent channels while decoding pictures of a currentchannel. In step 404, the de-mux 210 may be operable to store or bufferpictures in received one or more TSs from the video decoding system 100.In step 406, the processor 210 may be operable to determine or identifytiming information such as, for example, PTS values, RAPs and PCR valuesfor the current channel and each of the adjacent channels. In step 408,it may be determined whether the current channel needs to be processed.In instances where the current needs to be processed, then in step 410,a PCR rate may be determined or calculated based on the identified PCRvalue for the current channel to recover clock for decoding pictures ofthe current channel. In step 412, the video decoder 318 may be operableto decode pictures from the current channel buffer 314 utilizing thedetermined PCR rate.

In step 408, in instances where adjacent channels need to be processed,then in step 414. In step 414, a video primer such as the video primer316 may perform time stamp management on pictures in the adjacentchannel buffer 312. It may be determined whether PTS>PCR. In instanceswhere PTS>PCR, then in step 418, the video primer 316 may determinewhether PTS-PCR is less than a predetermined threshold value. Ininstances where PTS-PCR is less than the predetermined threshold value,then in step 420, corresponding pictures in the adjacent channel buffer312 may be set to be ready for decoding. In step 422, it may bedetermined whether the adjacent channel is selected. In instances theadjacent channel is selected, then in step 424, the video decoder 120may be operable to start decoding the pictures in the adjacent channelbuffer 312. In step 426, the video decoder 120 may be operable tocommunicate the resulting decoded pictures with the display device 130to present to users. The exemplary steps may return to step 404.

In step 414, in instances where PTS≤PCR, then in step 416, correspondingpictures in the adjacent channels 312 may be discarded if the next RAPis present. The exemplary steps may return to step 414.

In step 418, in instances where PTS-PCR is not less than thepredetermined threshold value, then the exemplary steps may return tostep 414.

In step 422, in instances the adjacent channel is not selected, then theexemplary steps may return to step 404.

In various exemplary aspects of the method and system for fast digitalchannel change utilizing time stamp management, a video streamdemultiplxer such as the de-mux 200 may be operable to receive one ormore video streams such as the TS 310 and 320 via the video decodingsystem 100. The received video streams may comprise a selected currentcontent channel and one or more content channels that are adjacent tothe selected content channel. A content channel may also be referred toas a channel or a program. The de-mux 200 may utilize a different videoprimer to concurrently perform time stamp management on each of the oneor more adjacent channels while decoding the selected current channelvia the video decoder 318. For example, the video primers 316, 324 and328 may be utilized or assigned to prime pictures in the adjacentchannel buffers 312, 322 and 326 in the CDB 230, respectively. The CDB230 may comprise the current channel buffer 228 and the adjacent channelbuffers 222-226 to store pictures for the selected current channel andeach of the adjacent channels, respectively.

Timing information may be determined for the stored pictures of theselected current content channel and the more adjacent content channels,respectively. The determined timing information comprises various timestamp values such as Decoding Time Stamp (DTS) values, and PresentationTime Stamp (PTS) values, and/or one or more random access points (RAPs).The de-mux 200 may be operable to determine a Program Clock Reference(PCR) value for each of the selected current channel and the adjacentchannels. A PCR rate may be determined for the selected current channelbased on the determined PCR value for the current channel. A timebasemay be derived or determined for the selected current channel based onthe determined PCR rate. The determined timebase may be provided as aclock reference to the video decoder 318 to decode pictures of theselected current channel. During decoding of the current channel, eachof the video primers 316, 324 and 328 may be operable to monitorcorresponding adjacent channel utilizing the determined PCR values.Pictures of the adjacent channels may be primed by the video primers fordecoding and displaying. Pictures for one of the adjacent channels, ifselected, may be directly decoded for display.

Other embodiments of the invention may provide a non-transitory computerreadable medium and/or storage medium, and/or a non-transitory machinereadable medium and/or storage medium, having stored thereon, a machinecode and/or a computer program having at least one code sectionexecutable by a machine and/or a computer, thereby causing the machineand/or computer to perform the steps as described herein for fastdigital channel change utilizing time stamp management.

Accordingly, the present invention may be realized in hardware,software, or a combination of hardware and software. The presentinvention may be realized in a centralized fashion in at least onecomputer system, or in a distributed fashion where different elementsare spread across several interconnected computer systems. Any kind ofcomputer system or other apparatus adapted for carrying out the methodsdescribed herein is suited. A typical combination of hardware andsoftware may be a general-purpose computer system with a computerprogram that, when being loaded and executed, controls the computersystem such that it carries out the methods described herein.

The present invention may also be embedded in a computer programproduct, which comprises all the features enabling the implementation ofthe methods described herein, and which when loaded in a computer systemis able to carry out these methods. Computer program in the presentcontext means any expression, in any language, code or notation, of aset of instructions intended to cause a system having an informationprocessing capability to perform a particular function either directlyor after either or both of the following: a) conversion to anotherlanguage, code or notation; b) reproduction in a different materialform.

While the present invention has been described with reference to certainembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted withoutdeparting from the scope of the present invention. In addition, manymodifications may be made to adapt a particular situation or material tothe teachings of the present invention without departing from its scope.Therefore, it is intended that the present invention not be limited tothe particular embodiment disclosed, but that the present invention willinclude all embodiments falling within the scope of the appended claims.

What is claimed is:
 1. A method, comprising: receiving, by a videodecoding system, a first coded picture of a first content channel and asecond coded picture of a second content channel adjacent to the firstcontent channel, the second content channel selected for decoding;storing the received coded picture of the first content channel, in afirst coded data buffer of the video decoding system, while decoding thesecond coded picture of the second content channel, determining, by avideo primer of the video decoding system, that a Presentation TimeStamp (PTS) of the stored coded picture of the first content channel isgreater than a current Program Clock Reference (PCR) value; responsiveto the determination, maintaining the stored coded picture of the firstcontent channel in the first coded data buffer; subsequentlydetermining, by the video primer, that the PTS of the stored codedpicture of the first content channel is not greater than a secondcurrent PCR value of the first content channel; and responsive to thedetermination that the PTS of the stored coded picture is not greaterthan the second current PCR value, discarding the stored coded pictureof the first content channel from the first coded data buffer.
 2. Themethod of claim 1, further comprising: decoding the stored coded pictureof the first content channel in the first coded data buffer, responsiveto a subsequent determination that a difference between the PTS of thestored coded picture of the first content channel and the PCR value ofthe first content channel is less than a predetermined threshold.
 3. Themethod of claim 1, further comprising: receiving a request to change tothe first content channel; and providing the stored coded picture of thefirst content channel from the first coded data buffer to a decoder ofthe video decoding system for immediate decoding and display, responsiveto the request.
 4. The method of claim 1, further comprising:determining timing information for the first content channel and theselected current content channel.
 5. The method of claim 4, wherein thetiming information comprises a Decoding Time Stamp (DTS) value, a PTSvalue, or one or more random access points (RAPs).
 6. The method ofclaim 1, further comprising identifying a timebase for the selectedcurrent content channel based on a PCR rate.
 7. The method of claim 6,further comprising decoding the selected current content channelutilizing the identified timebase.
 8. The method of claim 1, furthercomprising: storing a received second coded picture of a third contentchannel, adjacent to the selected current content channel or the firstcontent channel, in a second coded data buffer of the video decodingsystem; determining, by the video primer, that a Presentation Time Stamp(PTS) of the stored second coded picture is greater than the currentProgram Clock Reference (PCR) value; and responsive to thedetermination, maintaining the stored second coded picture of the thirdcontent channel in the second coded data buffer.
 9. A system,comprising: a first coded data buffer configured to store a receivedcoded picture of a first content channel, adjacent to a selected currentcontent channel; and a video primer configured to determine that aPresentation Time Stamp (PTS) of the stored coded picture is greaterthan a current Program Clock Reference (PCR) value, and responsive tothe determination, maintain the stored coded picture in the first codeddata buffer; and a decoder configured to decode the selected currentcontent channel responsive to a determination that a difference betweena PTS of a coded picture of the selected current content channel and thecurrent PCR value is less than a predetermined threshold, by the videodecoding system, while maintaining the stored coded picture in the firstcoded data buffer, responsive to the determination that the PTS of thestored coded picture is greater than a current PCR value; wherein thevideo primer is further configured to: determine that the PTS of thestored coded picture is not greater than a second current PCR value, anddiscard the stored coded picture from the first coded data buffer,responsive to the determination that the PTS of the stored coded pictureis not greater than the second current PCR value.
 10. The system ofclaim 9, wherein the decoder is further configured to decode the storedcoded picture in the first coded data buffer, responsive to a subsequentdetermination that a difference between the PTS of the stored codedpicture and the PCR value is less than the predetermined threshold. 11.The system of claim 9, further comprising: a user interface forreceiving a request to change to the first content channel; and adecoder configured to decode the stored coded picture from the firstcoded data buffer for display, responsive to the request.
 12. The systemof claim 9, wherein the video primer is further configured to: determinetiming information for the first content channel and the selectedcurrent content channel.
 13. The system of claim 12, wherein the timinginformation comprises a Decoding Time Stamp (DTS) value, a PTS value, orone or more random access points (RAPs).
 14. The system of claim 9,wherein the video primer is further configured to identify a timebasefor decoding the selected current content channel based on a PCR rate.15. The system of claim 9, further comprising a second coded data bufferconfigured to store a received second coded picture of a second contentchannel, adjacent to the selected current content channel or the firstcontent channel; and wherein the video primer is further configured todetermine that a Presentation Time Stamp (PTS) of the stored secondcoded picture is greater than the current Program Clock Reference (PCR)value, and responsive to the determination, maintain the stored secondcoded picture in the second coded data buffer.
 16. A method, comprising:receiving a plurality of content channels, by a video decoding system,each content channel comprising a bitstream of encoded pictures, eachcontent channel adjacent to at least one other content channel of theplurality of content channels; decoding, by a decoder of the videodecoding system, a first encoded picture of a first content channel ofthe plurality of content channels, responsive to a selection of thefirst content channel by a user of the video decoding system andresponsive to a difference between a Presentation Time Stamp (PTS) ofthe first encoded picture and a current Program Clock Reference (PCR)value being less than a predetermined threshold; storing, by the videodecoding system in a first coded data buffer, a second encoded pictureof a second content channel adjacent to the first content channel;maintaining the second encoded picture in the first coded data buffer,by a video primer of the video decoding system, while a PTS of thesecond encoded picture is greater than the current PCR value;subsequently determining, by the video primer, that the PTS of thesecond encoded picture is not greater than a second current PCR value;and responsive to the determination that the PTS of the second encodedpicture is not greater than the second current PCR value, discarding thesecond encoded picture from the first coded data buffer.